1. Field of the Invention:
The present invention relates to imaging systems. More specifically, the present invention relates to systems for providing multiple simultaneous images.
While the present invention is described herein with reference to a particular embodiment for an illustrative application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teaching provided herein will recognize additional modifications, applications and embodiments within the scope thereof.
2. Description of the Related Art:
In many applications there is a need to provide a wide angle view and also one or more high resolution zoom views. This normally requires one sensor per view. It would be advantageous to provide all of these views from a single sensor. For example, in forward looking infrared (FLIR) systems many situations arise in which simultaneous wide angle and zoom views of a scene would be desirable. A wide angle view may be used to find and designate targets while zoom views of each of the targets may be used to identify each target and aim the weaponry if necessary. For example, a driver may require a wide angle field-of-view and a gunner may require simultaneous zoom views of particular portions of a scene.
Previously, in order to achieve both a wide angle field-of-view and one or more zoom views, imaging systems required one set of lenses and associated optical equipment for each field-of-view desired. Typified by boresighted optical fields-of-view, these systems often included an optical field-of-view switch which would be activated whenever the operator desired an alternate view. Unfortunately, there are several limitations associated with the simple provision of sequential optical arrangements to provide sequential fields-of-view of an object in real time.
To the extent that systems equipped with such sequential optical arrangements provide sequential images of a scene, the zoomed image is generally confined to the center of the wide angle field-of-view. This common boresight limitation prevents a second operator from zooming in on a portion of the image near the border of the wide angle field-of-view.
In addition, a particularly significant limitation of the sequential optical arrangement approach is that these systems do not provide simultaneous images per se. That is, as only one set of optics may be selected at a time, only one view is available at a time. This is an obvious limitation in situations in which it is desirable to provide a field-of-view for more than one operator at a time such as for military systems.
An additional limitation of the sequential optical arrangement approach is that the magnification of the lenses is usually fixed and discretely limited. Only one magnification is available at a time.
Multiple simultaneous optical arrangements overcome some of the problems associated with sequential optical arrangements by providing multiple simultaneous images, but these systems can add significantly to the cost, size and weight of an imaging system. (This is particularly problematic with respect to FLIR systems which are generally expensive). These systems are generally mechanically complex and have close manufacturing tolerances which require precision assembly and maintenance. Further, multiple simultaneous optical arrangements generally increase the weight on the gimbal supporting the sensor and thereby limit the performance of the host system. When the optical arrangements share a common focal plane, they reduce scan efficiency (since each view utilizes only a fraction of the scan).
Finally, there are many systems in the field for which this capability of displaying multiple simultaneous images would be desirable. Yet, the retrofit of existing systems to provide this limited conventional capability would be too expensive to provide a practical option.
Providing multiple fields-of-view from a single optical arrangement solves many of the problems associated with multiple simultaneous optical arrangements. For example, copending U.S. Pat. application Ser. No. 07311785, filed by R. Zwirn on Feb. 14, 1989, discloses a technique for accomplishing simultaneous fields-of-view from a single optical arrangement. However, this system requires one display for each field-of-view.
Thus, there is a need in the art for an inexpensive nonmechanical system or technique for providing multiple simultaneous real time images with varying fields-of-view on a single display. Ideally, the system would allow for a ready (noninvasive) retrofit into existing systems and would not degrade the performance thereof.